In recent years, an acceleration sensor is widely used in mobile information equipment such as a smart phone, a tablet PC, and a mobile game machine. As the typical acceleration sensor, there are known the acceleration sensors of a capacitance type (e.g. Patent Literature 1), a piezo resistance type (e.g. Patent Literature 2), and a gas type (e.g. Patent Literature 3, Patent Literature 4, and Patent Literature 5).
The acceleration sensor of the capacitance type or the piezo resistance type uses a MEMS (Micro-Electro Mechanical Systems) device. In detail, “a mechanical movable portion” is formed in the semiconductor chip by use of the MEMS technique. The movement of the movable portion due to the acceleration to the semiconductor chip is detected through a change in capacitance or piezo resistance. However, the formation of the mechanical movable portion in the semiconductor chip is not desirable in the viewpoints of reduction of a production yield and increase of a manufacturing cost.
In case of the acceleration sensor of the gas type, a heater and a temperature sensor are disposed in a space formed in the semiconductor chip, and moreover a gas is injected and sealed into the space. The gas moves in the space due to the acceleration to the semiconductor chip, so as to change the temperature distribution of the gas. The acceleration to the semiconductor chip is detected by detecting the change of the temperature distribution of the gas by the temperature sensor. In case of this gas type acceleration sensor, “the mechanical movable portion” is unnecessary, which is desirable from the viewpoints of the production yield and the manufacturing cost.
Note that the following techniques are known regarding to a general sensor. Patent Literature 6 discloses a method of attaching the whole package of the acceleration sensor in perpendicular to a printed circuit board. Patent Literature 7 discloses a method of arranging a magnetic sensor on a substrate of a tapered shape.